Tappet



' bearin Patented Nov. Il, i924.

tra?

GEORGE f Rf. RICH, OF BATTLE CREEK, MICHIGAN, ASSIGNOR TO RICH STEELPRODUCTS COMPANY, OF BATTLE CREEK, MICHIGAN, A CORPORATION OFCALIFORNIA.

TAPPET.

Application led April 8, 1924. Serial No. 704,949.

To aZZ whom it may concern:

Be it known that I, GEORGE R. RICH, a citizen of the United States, anda resident of Battle Creek, Calhoun County, and State of Michigan, haveinvented certain new and useful Improvements in Tappets, f which thefollowing is declared to be a full, clear, and exact description.'

This invention relates to valve tappets for internal combustion enginesand its principal object is to protect the bearing face of the head ofthe tappet and provide against rapid deterioration thereof by the actionof the cam thereon, particularly when the tappet is new or when themotor or engine is first operated.

It is well known that because of improper lubrication, improperalignment of the cam shaft and of the tappets, and because ofimperfections in the bearing faces of the cams and for various otherreasons, the cams rapidly wear away the true bearing faces of the tappetheads, thereby interfering with the proper lifting and seating of thevalves,

and causing annoying clicking noises be-v.

tween the tappets and valves and between the tappets and cams.

In the usual process of machining and hardening valve tappets the hardouter surface portion is often removed in grinding the bearing face of atappet head thereby exposing the relatively softer metal of the head tothe action of the cam, with the result that the cam soon wears away thetrue face of the tappet. In the operation o a motor at normal speed thecam travels over the head of the tappet so rapidly and in such rapidsuccession that the lubricating oil scarcely has time to cover thebearing face of the tappet head between the successive revolutions ofthe cam, the result being undue wear and permanent injury to the truebearing face of the tappet head. Moreover when newly installed, theassociated bearing surfaces of the tappets and cams, although nicelyground, are raw, and under the microscope present innumerable pits andsharp edges; these raw faces must be worn down to obtain smoothness ofaction, and the wear occasioned makes a difference in thel lifting andseating movements of the tappet.

I have discovered ,that greater eiiiciency of operation is obtained,greater precision and smoothness of action results and that n oise isminimized, by providing a protect1ve metallic covering or surfacing forthe bearing face of the tappet head, which covering fills the pores atthe surface and presents a smooth anti-friction surface .to the cam,which surface, under the influence of the cam, is rendered stillsmoother, the anti-friction material is permanently embedded in thepores and the whole surface becomes burnished, thereby providing apermanent smooth bearing surface, on which the friction between the camand tappet is reduced to a minimum.

In the course of my experiments I have found that by tinning the bearingface of the tappet head, excellent'results are obtained and further,that bythe use of composite anti-friction bearing materials, such as tinand pulverized bronze, a most effective result is obtained. In somecases the use of pulverized iron, united to the bearing face by a morefusible metal, such as tin, has served the purpose with a remarkabledegree of success.

To such ends this invention consists in a valve tappet for internalcombustion engines having a head formed with a bearing surface, to whichis applied-an antifriction bearing material that covers the raw metaland protects it against the abrasive action of the cam. It furtherconsists in a valve tappet having a head formed with a bearing surfaceand a coating thereon united with said bearing surface and forming aprotective cover therefor. It furtherconsists in a valve tappet formedwith a head having a tinned bearing surface. It further consists inavalve tappet formed with a head having a bearing surface covered withpulverized bronze united thereto by a readily fusible metal. It furtherconsists in the several other novel features hereinafter fully set forthand claimed.

The invention is clearly illustrated in the drawing accompanying thisspecification, in which:

Fig. 1 is a side elevation of a tappet, embodying a simple form of thepresent invention, and an associated cam, the cam shaft being shown incross-section; Fig. 2 is a side elevation of the parts seen in Fig. 1lookin at right angles thereto; Fig. 3 is an en view of the tappet seen.in Fig. l with a portion of the coating or surface material removed fromthe bearing face of its head;

Fig. 4 is a detail, ragmental, longitudinal section through the tappet,showing its con dition prior to the app ication of the protectivecovering thereto, and Fig. 5 is a view similar to Fig. 4 with theaddition of the protective covering thereto.

Referring to said drawing, which illus trates one embodiment of thepresent inven-1 tion, the reference character 6 designates the valvetappet formin the subject matter of this speci cation, 7 esignates anassociated cam, and 8 a fragment of the acarn shaft upon which the camis formed. lin accordance with the usual practice the tappet comprisesthe stem portion 9 which is ordinarily mounted in suitable bushings orbearings in the motor and said stem may be hollovv if desired, as seenin Figs. Ll and 5, although this is not essential to the presentinvention. 'lhe tappet head `l() is shown as of the mushroom type and isformed with the bearing face l1, with which the cam 7 contacts. rllhebearin face 1,1 of the tappet head is shown as dat ut this is notnecessary as it may be crowned if so desired and in many cases this ispreferred. 'lhe tappet is held down upon the cam by a spring (not shown)as is well understood and the upper end of the tappet is provided withmeans ior engaging with or for actuating the valve, but as these partshave no bearing upon the present invention they will not be described indetail. As is well understood, the cam shaft rotates, and rotates thecam 7 and during each rotation of the .shaft the high part of the camlifts the tappet, thereby unseating the valve, and the spring lowers thetappet when the high part ofthe cam passes the head of the tappet.

As is customary, the tappet is formed from a rod of suitable metalpreferably from steel alloy, and the head is formed upon the stem bysuitable dies. ln the process of harden-A ing, machining and finishingthe tappet, the bearing face 1l is ground oil nicely, but

-`when observed under a microscope, in-

numerable pits and sharp edges and rough spots are observed on saidbearing face.

The same may be said of the cam. When the raw bearing face of the camrubs upon the raw bearing -faoe of the tappet head, especially if theyare not properly lubricated, the bearing face of the tappet head israpidly and unevenly worn away and sometimes edges of the cam cutgrooves in the bearing face of the tappet head, with the result that itstrue bearing face is distorted and worn away to such a degree that thelifting and seating of the valve by the tappet is changed, therebyreducinothe etlicency of the motor, besides producing annoying, clickingnoises.

In place of permitting the raw bearing surfaces of the cam and tappethead to contact with each other, l coat the bearing face ot the tappethead with a metdlic protective material l2, which in one form maycomprise tin, and in another form may comprise tin containing pulverizediron, but in its preferred form it comprises tin containpulverizedbronze. Said coating may, however, comprise any antiiriction materialthat may be united with the bearing lace of the tappet head and as anexample, Babbitt metal may be employed.

ln the process of forming a. Atappet con.- ta'ining the presentinvention., the tappet is first formed, ground. and nished in theordinary manner, after which the coating is applied to its head. lnapplying the coating, the coating material is kept upon a hot plate, andthe tappets are heated up to a temperature of approximately 200 degrees;the bearing ita/ce of each tappet is then dipped into a pro er solutionof acid immediately plan on the' hot plate containing the surfacingmaterial, which plate is preferably kept at a temperature oit'approximately 4:50 degrees, and the bearing face of the tappet is rubbedover and through the surfacing material contained on the plate until thequantity required, unites with the bearing face of the tappet, alterwhich the face is immediately wiped ed with a piece ot' felt or likematerial and the tappet is dropped into a cooling bath.

lV hen composite metals such as tin and bronze are used for coating thebearing face of the tappet head, the bronze is pulverized and it isadded to the tin, as much brenne being used as will be absorbed by thetinn 'lhe tin melts at the temperature to which 'the surfacing materialis exposed,vbut the bronze does not, necessarily, but is trans eried inits pulverized state, to the bearing face of the tappet when the latteris rubbed upon the hot plate containing the materials, and the bronze isthereby united to the bearing tace by the tin. 'lhc use of bronze hasbeen 'found to be highly' desirable because of its anti-frictionqualities.

F rom my observations of the results obtained by the use of a protectivecovering for the bearing faces of tappet heads, l dnd that the action ofthe cam on the bemg face is to impact or force the surfacing inaterialor at least a part of same, further into the pores of the metal and toburnish or polish the bearing face of the tappet head withoutperceptibly Wearing away any oj the metal of the head itself. Moreover lhave observed that some of the surfacing material is absorbed by thecam, which. indicates that both bearing surfaces oid the tappet and cambecome perfectly smooth y without any appreciable Wear thereon welWithout any distortion.

l claim as new, and desire to secure by Letters Patent:

l. A tappet having a head formed a lill@ Lamme i y i8 groundbearing face4adapted.I for engagebearing' face, adapted for engagement with A mentwith fi-cam, said bearing -eceherving aeem, said bearing face havlngulverized ay metallic, anti-friction surface protecting bronzeunitedtoit by a more fusa 'le metal.

I' material thereonvand united therewith. I` 4. .A tappetheving a. headformed with 5 2. A tappet havingY a heed formed with agroundbearingrface, adapted for engage- 15 a bearing face, adapted forengagement with ment with a eem, said bearface having a cam, saidbearing face being coated with ulveriz'ed anti-friction meta united toit e ellettallic composition containing pulverby amore fusible metal.

- iz ronze.

1o a. n tappe, having a. head formed with. a, g f GEORGE 3.111011.

